Needle with optical fibers

ABSTRACT

Needle interventions are widely used in the field of oncology for taking biopsies of tissue in order to inspect whether tissue is cancerous or not. To make these interventions more reliable feedback of what kind of tissue is in front of the needle is required. A way to achieve this is by making use of optical spectroscopy. This requires integration of fibers into the needle. These fibers are used to deliver light to illuminate the tissue in front of the needle and to collect back the reflected light from the tissue. The present invention proposes to integrate the fiber distal ends in the slanted bevel of the needle in such a way that at least one source-detector fiber pair has a distance that is larger than the outer diameter of the needle.

FIELD OF THE INVENTION

The invention generally relates to a needle with optical fibers.Particularly, the invention relates to a small diameter needle fortissue inspection based on optical spectroscopy to diagnose whethertissue is cancerous or not.

TECHNOLOGICAL BACKGROUND

Needle interventions are widely used in the field of oncology for takingbiopsies of tissue in order to inspect whether tissue is cancerous ornot. To make these interventions more reliable feedback of what kind oftissue is in front of the needle is required. A way to achieve this isby making use of optical spectroscopy. This requires integration offibers into the needle. These fibers are used to deliver light toilluminate the tissue in front of the needle and to collect back thereflected light from the tissue.

An important feature that can be used in discriminating tissue is theabsorption peaks present in the reflectance spectra. In general theabsorption of tissue in the visible range is rather low (typically theabsorption coefficient μ_(a)=0.1 cm⁻¹). This means that when thesource-detector fiber ends are close to each other, the effect of theabsorption becomes rather small on the spectra and as a result difficultto detect.

Various needle interventions such as taking biopsies could benefit fromthis kind of tissue characterization in front of the needle. However,these needle interventions have a strong drive to have needles with anas small as possible outer diameter in order to reduce the trauma of thepatient as much as possible. As a result, this drive towards small outerdiameter needles is in conflict with the requirement that the fibersshould be as far as possible apart in order to have detectableabsorption features in the measured reflectance spectra.

Various fiber optic probes are described in literature such as in “Fiberoptic probes for biomedical optical spectroscopy” by U. Utzinger and R.R. Richards-Kortum in Journal of Biomedical Optics volume 8 (2003)p121-147. These probes have in general blunt probe ends resulting infiber end distances that are smaller than the diameter of the probe.

SUMMARY OF THE INVENTION

It might be an object of the invention to integrate the source-detectorfibers into the needle tip such that the outer diameter of the needle issmall while still having a detectable absorption feature in the measuredreflectance spectra.

These might be achieved by the subject matter according to each of theindependent claims. Further embodiments of the present invention aredescribed in the respective dependent claims.

Generally, a needle according to the invention comprises a shaft, a tipat a distal end of the shaft, wherein the tip of the needle is formed bya bevel, a first fiber, the first fiber being capable of transmittinglight, wherein an end surface of the first fiber is located at a top ofthe bevel, and a second fiber, the second fiber being capable oftransmitting light, wherein end surface of the second fiber is locatedat a bottom of the bevel.

The bevel of the needle is in general slanted in order to allow easyentry into the tissue. Therefore, with ‘bevel’ is meant a geometricalstructure allowing for introducing the needle into tissue. Usually, ashaft of a needle includes a circular cross section. The distal end of aneedle shaft, in particular of a shaft of a hollow needle, is cut suchthat an oval surface is formed, which is inclined relative to thelongitudinal axis of the shaft. Further, there is defined an anglebetween the longitudinal axis of the shaft and the inclined surface,i.e. the bevel. The bevel forms a pointed tip at the most distal end ofthe needle. Furthermore, the edge between the outer surface of the shaftand the inclined surface of the bevel might be sharpened.

The wording ‘top of the bevel’ should indicate an area being part of thesurface of the bevel, which area is located adjacent to the distal edgebetween the bevel and the shaft. That is, a fiber which is located atthe top of the bevel might be located at the long axis of the ovalsurface of the bevel, near the distal edge, i.e. the pointed tip.

On the other hand, ‘bottom of the bevel’ means the area being part ofthe surface of the bevel, which area is located diametric to the top ofthe bevel. That is, the fiber which is located at the bottom of thebevel might be on or near or adjacent beside the long axis of the ovalsurface of the bevel near the proximal edge between bevel and shaft.

However, the wording ‘bevel’ might also enclose similar structures atthe tip of the needle, which structures are useful for introducing theneedle into a tissue. For example, the bevel might be a convex orconcave surface, or the bevel might be a combination of several smallsurfaces, wherein these surfaces are connected to each other by steps oredges. It might also be possible that the cross section of the shaft isnot completely cut by the bevel, such that an area remains which isblunt, i.e. is perpendicularly orientated relative to the longitudinalaxis of the shaft. Such a ‘blunt’ end might include rounded edges ormight also form a rounded leading edge. As another exemplary, a sharpedge might be formed by two or more slanted surfaces being symmetricallyor asymmetrically arranged to form the tip of the needle.

According to one embodiment of the invention, the bevel forms an acuteangle with the shaft, such that the needle includes a pointed tip.Preferably, the acute angle is approximately 20°.

According to one embodiment of the invention, the shaft of the needlehas an outer diameter, and the end surface of the first fiber and theend surface of the second fiber are arranged at a distance to eachother. Preferably, the distance between the fiber ends is greater thanthe diameter of the shaft. For example, the distance is more than 1.1times greater than the diameter. Particularly, the distance is more than1.25 times greater than the diameter. Preferably, the distance is morethan 1.5 times greater than the diameter.

Depending on the intended use of the needle, the outer diameter of theneedle might be 2.108 mm for a brain biopsy needle, between 1.27 mm and2.108 mm for a common biopsy needle or a neuro puncture needle, between0.711 mm and 2.108 mm for a fine aspiration needle, between 0.711 mm and1.473 mm for an epidural needle, and might be 2.108mm or smaller for aneedle electrode.

According to a further embodiment of the invention, the needle furthercomprises a third fiber which is capable of transmitting light, whereinan end surface of the third fiber is located at the bottom of the bevelin the vicinity of the end surface of the second fiber. In this case,the second fiber and the third fiber might be located beside the longaxis of the bevel surface.

For example, with a needle diameter of 1.3 mm it might be possible thatthe distance between the fiber at the top of the bevel and one of thefibers at the bottom of the bevel might be 2.46 mm, and the distancebetween the two fibers at the bottom of the bevel might be 0.37 mm.

It is noted that the distances are measured from the central axis of oneof the fibers to the central axis of the other one of the fibers.

According to another embodiment of the invention, the shaft of theneedle is formed by an inner tube and an outer tube, wherein a space isprovided between the inner tube and the outer tube, in which space thefibers are accommodated.

According to yet another embodiment of the invention, the needle withfibers might be use in a system for optical tissue inspection, whereinthe system further comprises a light source connected with one of thefibers of the needle, a light detector connected with another one of thefibers of the needle, wherein light coming from the light source andbeing emitted from the end surface of the one of the fibers can bedetected by the light detector when entering the other one of thefibers, a processing unit for processing the data from the lightdetector, and a monitor for visualization of the processed data.

In such a system, the fiber distal ends in the needle slanted bevelprovide at least one source-detector fiber pair with a distance A thatis larger than the outer diameter of the needle D, wherein A>1.1D oreven A>1.25D, and preferably A>1.5D. If b is the tip angle of the needlebevel the following equation might count

$\begin{matrix}{\frac{A}{D} > \frac{{\sin \; b} + 0.1}{\sin \; b}} & (1)\end{matrix}$

In the case that the needle is provided with a first fiber at the top ofthe bevel, and with second and third fibers at the bottom of the bevel,the first fiber might be serve as a light source emitting light intosurrounding tissue, and the second and third fibers might be twodetector fibers collecting reflected light.

The invention might also be related to a computer program for theprocessing unit of the system according to the invention. The computerprogram is preferably loaded into a working memory of a data processor.However, the computer program may also be presented over a network likethe worldwide web and can be downloaded into the working memory of adata processor from such a network. The computer program might controlthe emitting of light, might process the signals coming from the lightdetector at the proximal end of the detector fiber(s). These data mightthen be visualized at a monitor.

It has to be noted that embodiments of the invention are described withreference to different subject matters. In particular, some embodimentsare described with reference to application steps whereas otherembodiments are described with reference to devices or systems. However,a person skilled in the art will gather from the above and the followingdescription that, unless other notified, in addition to any combinationof features belonging to one type of subject matter also any combinationbetween features relating to different subject matters is considered tobe disclosed with this application.

The aspects defined above and further aspects, features and advantagesof the present invention can also be derived from the examples ofembodiments to be described hereinafter and are explained with referenceto examples of embodiments. The invention will be described in moredetail hereinafter with reference to examples of embodiments but towhich the invention is not limited.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 shows a cross section of the tip portion of a needle according toa first embodiment of the invention.

FIG. 2 shows a front view of the needle according to the firstembodiment of the invention.

FIG. 3 shows a front view of a needle according to a second embodimentof the invention.

FIG. 4 is an isometric illustration of a tip portion of a needleaccording to the second embodiment of the invention.

FIG. 5 is a schematic illustration of a system according to theinvention, the system including a needle according to a third embodimentof the invention.

The illustration in the drawings is schematically only and not to scale.It is noted in different figures, same or similar elements are providedwith the same reference signs.

DETAILED DESCRIPTION OF EXEMPLARY EMBODIMENTS

FIG. 1 is a cross sectional view of the tip portion of a needleaccording to a first embodiment of the invention. The needle 100includes a shaft 110 having a longitudinal axis or centre axis 150.Parallel to the centre axis, there are formed two bores or channels, inwhich fibers 130, 140 are located, respectively. These fibers, namelythe first fiber 130 and the second fiber 140, include end surfaces 132,142, respectively.

Further, the shaft 110 is cut at its distal end, such that a bevel 120is formed. The bevel 120 is a slanted surface which can be divided in anarea named as top 122 of the bevel, and an area named as bottom 124 ofthe bevel. Further, the bevel 120 enclose an angle b with the centeraxis of the shaft 110. The angle b is preferably an acute angle ofapproximately 20°.

The end surface 132 of the first fiber 130 is located at the top of thebevel and the end surface 142 of the second fiber 140 is located at thebottom of the bevel. After positioning the ends of the fibers in thechannels or bores in the shaft, the bevel together with the ends of thefibers might be polished. By way of this, a smooth or even surface mightbe achieved including two end surfaces of fibers, wherein such polishedend surfaces provide for good optical characteristics.

As further depict in FIG. 1, a distance A is defined, which is measuredfrom a middle of the end surface 132 of the first fiber 130 to themiddle of the end surface 142 of the second fiber 140.

FIG. 2 is a front view of the needle according to the first embodimentof the invention. FIG. 2 shows the bevel 120 together with the endsurface 132 of the first fiber and the end surface 142 of the secondfiber. Furthermore, the usually circular cross section of the shaft ofthe needle 100 defines a diameter D. The distance A (see FIG. 1) islarger than the outer diameter D of the needle, wherein A>1.1D or evenA>1.25D, and preferably A>1.5D.

With b as the tip angle of the bevel, the following equation might count

$\begin{matrix}{\frac{A}{D} > \frac{{\sin \; b} + 0.1}{\sin \; b}} & (1)\end{matrix}$

In the case of the first embodiment, in which the needle is providedwith a first fiber at the top of the bevel, and with a second fiber atthe bottom of the bevel, the first fiber might serve as a light sourceemitting light into surrounding tissue, and the second fiber might serveas a detector fiber collecting reflected light.

FIG. 3 is a front view of a needle according to a second embodiment ofthe invention. Generally, the second embodiment is similar to the firstembodiment. The second embodiment also includes a shaft, a bevel formingan acute angle with the shaft, a first fiber at the top of the bevel,and a second fiber at the bottom of the bevel.

Additionally, the needle according to the second embodiment comprises athird fiber with an end surface 252. The third fiber is arranged in achannel or through bore which is formed parallel to the centre axis ofthe shaft and, thus, parallel to the channels of the first and secondfibers. Further, the end surface 252 of the third fiber is located inthe vicinity of the end surface of the second fiber, at the bottom 224of the bevel 220.

In the case of the second embodiment, in which the needle is providedwith a first fiber at the top of the bevel, and with second and thirdfibers at the bottom of the bevel, the first fiber might serve as alight source emitting light into surrounding tissue, and the second andthird fibers might serve as detector fibers collecting reflected light.

FIG. 4 shows the tip portion of the needle according to the secondembodiment as an isometric view. This view illustrates that the actualshape of the surface of the bevel as well as of the end surfaces of thefibers is substantially oval.

FIG. 5 illustrates a system according to the invention. The systemincludes a needle 300 according to a third embodiment of the invention.In this illustration, the needle 300 is an assembly of a tip part 310,an inner tube 352, an outer tube 350, and a holder part 360.Furthermore, two fibers 330 and 340 are shown in the needle. Animportant part of the needle is the needle tip, in which two or threebores are manufactured. In each bore a fiber is mounted, by gluing. Thetip is fixed to both inner tube and outer tube by welding or gluing,wherein the inner and outer diameters of the inner and the outer tubeare adapted to correspond respective structures at the proximal shaftsection of the tip part. A space 356 between the tubes might beachieved, into which the through bores in the tip part are open out.Coming out of the bores of the tip part, the fibers 330, 340 arepositioned in the hollow space 356 between both tubes.

The tip, fibers and both tubes, once assembled, are fixed to a needleholder. Inside the holder the inner tube is connected with a connectorto which for instance a syringe or other tubing can be fixed. In thisway volumes of fluid can be dispensed through the channel 354 of theinner tube and tip part, without interaction with the fibers. The needleholder 360 also contains separate exit 362 for the fibers. Afterassembling tip, fibers, tubes and holder, the bevel 320 of the needle(i.e. the needle tip) is polished to obtain a proper surface quality forthe fibers.

To have appropriate properties of the different parts of the needle, thetip part might be made of a metal, an alloy or ceramic material, and theshaft tubes might be made of a metal material, wherein the metalmaterial should be MRI compatible, for example titanium.

Further, the system comprises a light source 332, a light detector 242,a processing unit 370 and a monitor 380. The processing unit 370 iscapable of controlling the light source 332 to emit light into the fiber330 such that light will be emitted through the distal end surface ofthe fiber 330 at the top of the bevel 320 into surrounding tissue.Depending on what kind of tissue is in front of the bevel, more or lessof the emitted light will be reflected in the direction of the bottom ofthe bevel, to be received be the other fiber 340. Through the fiber 340,the light will is led to the light detector 342, which detector isadapted to transform the light into electrical signals. These electricalsignals will be send by, for example, wire to the processing unit. Theprocessing unit will process the data corresponding to the electricalsignals, so that the processed data might be visualized on a monitor380. Based on said visualized data, it might be possible to diagnosewhether or not a tissue is cancerous.

In the following, exemplary needles according to the invention will bedescribed with respect to their outer diameter, their insertion length,and their preferred use.

A biopsy needle might have an outer diameter of 1.27 mm up to 2.108 mm,might be inserted into tissue with 100 mm to 150 mm of its length, andmight be used in soft tissue core biopsies in the neck, the head, thebreast, the prostate, and the liver.

A fine aspiration needle of soft tissue might have an outer diameterbetween 0.711 mm and 2.108 mm, might be inserted into soft tissue with100 mm to 150 mm of its length, and might be used for aspiration of softtissue.

A brain biopsy needle might have an outer diameter of 2.108 mm, might beinserted into tissue with 150 mm up to 250 mm of its length, and mightbe used for diagnostic brain biopsies.

A neuro puncture needle might have an outer diameter of 1.27 mm up to2.108 mm, might be inserted into tissue with 150 mm to 200 mm of itslength, wherein such needles allow a non-traumatic approach to lesionsin the brain.

An epidural needle might have an outer diameter between 0.711 mm and1.473 mm, might be inserted into tissue with a length of up to 150 mm,and might be used for treatments in the spinal cord area such as steroidinjections in the epidural space.

Finally, a needle electrode might have an outer diameter of 2 108 mm andsmaller, might be inserted into tissue up to 250 mm of its length, andmight be used for radiofrequency ablation for instance of tumors.

While the invention has been illustrated and described in detail in thedrawings and foregoing description, such illustration and descriptionare to be considered illustrative or exemplary and. not restrictive; theinvention is not limited to the disclosed embodiments.

Other variations to the disclosed embodiments can be understood andeffected by those skilled in the art in practicing the claimedinvention, from a study of the drawings, the disclosure, and theappended claims. In the claims, the word “comprising” does not excludeother elements or steps, and the indefinite article “a” or “an” does notexclude a plurality. A processing unit may fulfill the functions ofseveral items recited in the claims. The mere fact that certain measuresare recited in mutually different dependent claims does not indicatethat a combination of these measures cannot be used to advantage. Acomputer program may be stored/distributed on a suitable medium, such asan optical storage medium or a solid-state medium supplied together withor as part of other hardware, but may also be distributed in otherforms, such as via the Internet or other wired or wirelesstelecommunication systems. Any reference signs in the claims should notbe construed as limiting the scope.

LIST OF REFERENCE SIGNS

100, 200, 300 needle

110, 210 shaft

120, 220, 320 bevel

122 top of the bevel

124, 224 bottom of the bevel

130, 330 first fiber

132, 232 end surface of first fiber

140, 340 second fiber

142, 242 end surface of second fiber

150 longitudinal axis of needle

252 end surface of third fiber

310 tip part

332 light source

342 light detector

350 outer tube

352 inner tube

354 channel

356 space between inner and outer tubes

360 holder part

362 opening

370 processing unit

380 monitor

1. A needle (100, 200) comprising a shaft (110, 210), a tip at a distalend of the shaft, wherein the tip of the needle is formed by a bevel(120, 220), a first fiber (130, 230), the first fiber being capable oftransmitting light, wherein an end surface (132, 232) of the first fiberis located at a top (122, 222) of the bevel, and a second fiber (140,240), the second fiber being capable of transmitting light, wherein endsurface (142, 242) of the second fiber is located at a bottom (124, 224)of the bevel.
 2. The needle of claim 1, wherein the shaft (110, 210) hasan outer diameter (D), wherein the end surface (132, 232) of the firstfiber and the end surface (134, 234) of the second fiber are arranged ata distance (A) to each other, wherein the distance (A) is greater thanthe diameter (D).
 3. The needle of claim 2, wherein the distance (A) ismore than 1.5 times greater than the diameter (D).
 4. The needle ofclaim 2, wherein the outer diameter (D) of the shaft (110, 210) isbetween 0.711 mm and 2.108 mm.
 5. The needle of claim 1, wherein thebevel (120, 220) forms an acute angle (b) with the shaft (110, 210),such that the needle includes a pointed tip.
 6. The needle of claim 5,wherein the acute angle (b) is 20°.
 7. The needle of claim 1, furthercomprising a third fiber, the third fiber being capable of transmittinglight, wherein an end surface (252) of the third fiber is located at thebottom (224) of the bevel in the vicinity of the end surface (242) ofthe second fiber.
 8. The needle (300) of claim 1, further comprising aninner tube (352) and an outer tube (350), wherein a space (356) isformed between the inner tube and the outer tube, wherein the fibers(330, 340) are accommodated in the space.
 9. A system for optical tissueinspection, the system comprising a needle (100, 200, 300) according toclaim 1, a light source (332) connected with one of the fibers (330) ofthe needle (300), a light detector (342) connected with another one ofthe fibers (340) of the needle (300), wherein light coming from thelight source and being emitted from the end surface of the one of thefibers can be detected by the light detector when entering the other oneof the fibers, a processing unit (370) for processing the data from thelight detector, and a monitor (380) for visualization of the processeddata.